"I often pondered the mindset that lay behind such an inhuman arrangement"
Which, presumably, you have decided was deliberate, rather than a thoughtless or unavoidable making do with the space to hand.
The first jazz club I ever attended (The Liverpool Cavern, in those halcyon pre-Beatle days) was laid out so "the performers would face the audience (as is the norm) but in doing so would be standing with their backs to" - record sleeves of past performers.
It seems to me this thread is made up of such presumptions, the only evidence of there ever having been "purists" being based on an animosity towards those not prepared to 'go with the flow' backed up by apocryphal tales of a far-distant, ill-remembered past.
The validity (or otherwise) of these claims is underlined for me by the tendency of those making such claims to ignore challenges and to scurry off to other threads when asked to put their money where their mouth is.
"Do purists really exist?"
Based on the 'evidence' presented here, no - and they probably never did to any significant extent, other than in the minds of those who feel it necesary to create straw men in order to give vent to their own likes and dislikes at the expense of other peoples' choices.
Jim Carroll